Rolling mill mandrel



Jan. 29, 1935. s. DIESCHER ROLLING MILL MANDREL Filed y 3. 1933 NUNPN ON \W/A .IIL I .y a L Q L Patented Jan. 29, 1935 i 1,989,507

UNITED STATES.- PATE OFFICE maaso'z A some MILL MANDREL Samuel E. Dieschcr, Pittsburgh, Pa., assign'or to Diescher Tube Mills, Inc., Pittsburgh, Pa., a corrotation of Delaware Application May 3, 1933, Serial No. 669,145

7 Claims. (01. 78-103) My invention relates to mandrels for use in in connection with the accompanying drawing, reducing the wall thickness of and elongating in which, tubular blanks, and particularly to mandrels tor Figure 1 is a view partially in horizontal secuse in producing tubes of relatively large diamtion and partially in plan of a portion of a tubueters by cross-rolling. lar blank provided with a mandrel embodying '5 In reducing the wall thickness and increasing one form of my invention, the blank being bethe length of a tubular blank by cross-rolling the tween the cross-rolls in an intermediate stage blank on a mandrel, it is necessary to employ a of its elongation and the reduction of its wall mandrel having an outside diameter which is not thickness; I

' much less than that of the interior of the com- Fig. 2 is a transverse section of the tubular l0 pleted tube. It will be appreciated that the blank and mandrel of Fig. 1 and associated appaweight of solid mandrels becomes proportionately ratus; greater relative to that of the tube as the di- Fig. 3 is a view similar to Fig. 1 of a modificaameter of the tube increases. tion;

In the operation of cross-rolling large diam- Fig. 4 is a transverse sectional view of the 15 eter tubes, no very great difiiculty is experienced tubular blank and apparatus of Fig. 3; in introducing solid mandrels of the necessary Fig. 5 is a longitudinal sectional view of the diameter into the cross-rolls with the work-piece, f rward porti n f the mandr l of Fi 3: but the weight of these mandrels is such that Fi 6 i a V w S ila to Fi 1 Of a fur h r they become diflicult to convey and may damage modification; and 20 the hot walls of completed thin wall tubes as Fig. 7 isa transverse sectional view of the tubuthey issue from the cross-rolls upon a delivery lar blank and apparatus of Fig. 6. table or other apparatus. Referring particularly to Figs. 1 and 2, man- In order to avoid the use of a solid mandrel of drels according to the invention may be used large diameter and at the same time provide a in-reducing the wall thickness and increasing 25 mandrel that is of sufiicie ht strength throughout the length of tubular blanks in a cross-roll mill its length to resist the forces exerted by the wallsuch, for example, as that shown and described reducing rolls upon the tubular blank in passing in my Patent No. 1,870,209, granted August 2, therethrough, I provide a mandrel of hollow con- 1932. Such a mill comprises two helically acting struction but provided with simple and eflicient cross-rolls 1, only portions of which are shown, 30 reinforcing means that is of such shape and conand two driven rotatable guide discs 2 which enstruction as to provide greater strength than an gage the blank between the cross-rolls 1. Atubuequivalent amount of solid material. Mandrels lar blank 3 is shown in an intermediate stage of this kind are adapted for cooling internally. of its passage through the mill, and a mandrel 4 36 In accordance with my invention, the interiors according to the invention is shown within the of the mandrels are gilled, that is, provided with blank.

a series of alternate circumferentially-extending The mandrel 4 comprises a hollow cylindrical ribs and grooves which provide greater strength member 5 that is provided upon its interior with for resisting the pressures of the cross-rolls than helical ribs 6 and intervening oov s 7 that ex- 0 would be afiorded by the ame amount of olid tend substantially throughout the length Of the 40 materiaL These ribs and grooves may be of mandrel. The ribs 6 and grooves 7 therebetween various construction and form Such as annular most desirably extend radially for a distance thathelicaL Furthermore, the ribs and grooves is relatively greater than the thickness of the solid may be formed directly upon the interior surfaces portmn of the hollow member of the man dr 618 or the The forward end of the mandrel 5 may be 45 y may be provided upon the interior surfaces of a series of removable provlded wlth sultaple comcal m Su-ch bushings as the head 8 shown m Fig. 5 1n connection with the mandrel of Figs. 3 and 4. It will be noted l q espe1a1 1y melded for reducmg the that the head 8 has a screw-threaded connecthmkness and mcl'esmg the length of large tion to the body of themandrel and is prevented 50 diameter tubular blanks 1n cross-rolling elongatfrom rotation relativelythereto by a rivet 9. mg mills, mandrels of the invention are adapted In order that the mandrel may be maintained for use in treating large diameter tubes in other at as low a temperature and consequently at a types of mills. strength that is as high as feasible, it is desirable as The details of my invention will be described to provide a cooling system therefor. In the construction shown, cooling water or other suitable cooling medium is supplied to the'interior of the hollow member 5 by means of a centrally disposed pipe or tube 10 that is spaced from the surrounding walls by means of supports comprising radial members 11 for engaging the tops of the ribs 6.- The open forward end of the tube 10 is adjacent to the conical head 8 and the return path for the cooling water is the space around the tube 10 including the grooves 7.

The ribs 6 constitute reinforcing means for the hollow member 5, and their effect is to give the mandrel a compression-resisting strength which is greater than if the thickness of the hollow member 5 were increased by an equivalent amount of solid material. The spaced ribs 6 increase the area of surface contact between the walls of the hollow member 5 and the cooling water, and the flow of the latter is facilitated by the helical shapeof the grooves 7. When the pipe 10 is of relatively small diameter, water may be supplied thereto under relatively high pressme in order to provide sufllciently rapid outward flow of water in contact with the surfaces to be cooled.

Reference may now be had to Figs. 3, 4 and 5, in which a modification of my invention is illustrated. Similar numerals designate like parts.

This embodiment of my invention differs principally from that of Figs. 1 and 2 in that the helical ribs and grooves 6 and 7 areprovided upon the interior of a series of cylindrical bushings 12 which occupy the interior of a relatively thin shell 13 of a mandrel 14. Also, the mandrel 14 is provided with a pipe 15 for cooling water that is larger than the pipe 10 previously referred to.

The bushings 12 may be of relatively short length and may be inserted in the bore of the tube 13 until the latter is reinforced throughout substantially its entire length. The principal advantages of this type of construction are that the bushings 12 are removable and in cases! wear of the shell or of damage either to the shell or the bushings, any of these parts may be removed to the extent that is necessary to replace them. The shell 13 may be of the same or diflerent materials, and each may be of such material as will best serve under the pressure and temperature conditions to which the mandrel is subjected.

The cooling system for the mandrel 14 of Figs. 3, 4 and 5 is substantially like that described in connection with the mandrel 4 of Fig. l, the cooling liquid entering through the tube 15 and returning in contact with the surfaces of the ribs and grooves in the bushings 12. In this arrangement, however, the supply tube is larger and the pressure may be adjusted to insure sufficiently rapid outward flow of a relatively thin film of water over the inner edges of the ribs. The bushings 12 conduct heat inwardly from the shell 13.

The construction of the mandrel 16 of Figs. 6 and 7-diflers from that of the mandrel 14 of Fig. 3 principally in that the series of circumferentially-extending ribs 17 and grooves 18 with which bushings 19 are provided are annular rather than helical, and the bushings 19 are shorter than the bushings 12 of Fig. 3. The length of these bushings will, however, be governed by the conditions governing their manufacture and the materials employed. Otherwise, the mandrel 16 does not differ materially from the mandrel 14. The cooling system is similar to that of the mandrel of Fig. 1. The mandrels may be mounted in any sultable manner for the purpose of providing connections to a source of water under pressure. For example, the mandrels may be secured to a mandrel-head on a suitable reciprocable carriage, the

mandrel head being provided with suitable connections for continuing the supply of water during longitudinal movement and rotation of the mandrel. An arrangement of this character is shown and described in the copending application of August P. Diescher, Serial No. 682,659,

filed March 25, 1933. Any other suitable mechanism may be employed for controlling the movements of the. mandrels or for supplying cooling water thereto, but such mechanisms constitute no part of the present invention.

Mandrelsconstructed in accordance with my invention are relatively light in weight while affording sufllcient strength to resist the forces exerted by cross-rolls in elongating a tubular blank upon the mandrel. The ribs provide reinforcing means for the wall of the hollow cylindrical unnecessary, in case of wear or damage to a portion of the mandrel, to discard the entire device as might be necessary when the outer shell is unitary with its reinforcing means.

The foregoing and other advantages will be apparent to those skilled in the art of construction and operation of apparatus for reducing and elongating tubular blanks upon mandrels.

. I claim:

1. A mandrel for use in reducing the wall thickness and increasing the length of tubular blanks comprising a hollow elongated body proper of substantially uniform cross section andclosed at one end thereof, helical ribs extending inwardly from the internal surface of said body and substantially along the length thereof to provide a central unobstructed passageway and a helical passageway in the grooves between said ribs, and

means for circulating a cooling medium along said passageway and said grooves.

2. A mandrel for use in reducing the wall thickness and increasing the length of tubular blanks comprising a hollow elongated body proper of,

substantially uniform cross section and closed at one end thereof, a series of hollow bushings within said body, and substantially throughout the length thereof, said bushings being provided with inwardly extending ribs and grooves alternating therewith to provide an unobstructed central passageway, and means for circulating a cooling medium along said passageway and in the grooves communicating therewith.

3. A mandrel for use in reducing the wall thickness and increasing the length of tubular blanks comprising a hollow elongated body proper of substantially uniform cross section and closed at one end thereof, a series of hollow bushings within said body, and substantially throughout the length thereof, said bushings being provided with inwardly extending helical ribs and grooves alternating therewith to provide a central passageway communicating with said grooves, and means for circulating a cooling medium through saidpassageway.

4. A mandrel for use in reducing the wall thickness and increasing the length of tubular blanks, comprising an elongated tubular body of substantially uniform cross section, thewinterior of the body being provided with annularlydisposed ribs extending inwardly from the internal surface thereof and throughout substantially the entire length thereof and formed to reinforce said body against pressure applied laterally of it.

5. A mandrel for use in reducing the wall thickness and increasing the length of tubular blanks, comprismgan elongated tubular body of substantially uniform cross section, the interior of the body being provided with helical ribs extending inwardly from the internal surface thereof and throughout substantially the entire length thereof and formed'toreinforce'said body against pressure applied laterally of it.

6. A mandrel for use in reducing the wall thick ness and increasing the length of tubular blanks. comprising an elongated tubular body of substantially uniform cross section, a series of hollow bushings fitted within said body and extending throughout substantially the entire length thereof, said bushings being provided with annularlydisposed ribs formed to reinforce said body against pressure applied laterally to it.

7. A mandrel for use in reducing the wall thick ness and increasing the length of tubular blanks, comprising an elongated tubular body of substantially uniform cross section and closed at one end thereof, annularly-disposed body-reinforcing ribs extending inwardly from the internal surface of said body and throughout substantially the entire length thereof to provide a central unobstructed passageway and an annularly-disposed passageway in the grooves between said ribs, and means for circulating a cooling medium along said passageway and grooves.

SAMUEL E. DIESCHER. 

